A MAID (Massive Array of Idle Disks) technology, e.g., is known as a method for controlling a storage device. The MAID technology is to shift a disk of a storage device of a RAID (Redundant Arrays of Inexpensive Disks) apparatus (RAID group) without being accessed to an idling state so as to suppress power consumption of the storage device. There is a method for controlling a disk motor of every RAID group by using the MAID technology. As a motor of a disk (disk device) in the RAID group is kept off for a longer period of time, the storage device may more reduce power consumption. Thus, an operation such that one and the same host or server accesses a logical volume in one RAID group and turns off a motor of a disk in another RAID group is disclosed. Further, e.g., an operation in a case where a volume in one RAID group is used by a plurality of servers such that the respective servers access a logical volume in the RAID group in similar periods of time is disclosed.
In a storage device group in which a virtual volume is built through Thin Provisioning, a logical volume is assigned from a pool area in a case where the virtual volume runs short of capacity. The pool area ordinarily includes RAID groups of individual levels, and some logical volume which forms each of the RAID groups is acquired as an area of the virtual volume. The number of RAID groups allotted to the virtual volume tends to increase if a file system adds and deletes data to and from the virtual volume repeatedly. As the number of the allotted RAID groups increases, the number of the storage devices grows somewhat larger with respect to an amount of frequently accessed data, resulting in an increase in power consumption.
The following are reference documents.
[Patent Document 1] Japanese Laid-open Patent Publication No. 2009-110451
[Patent Document 2] PCT International Application Publication No. WO2003/050707